Evans Ben J
Center for Environmental Genomics, Department of Biology, Life Sciences Building Room 328, 1280 Main Street West, McMaster University, Hamilton, ON, Canada L8S 4K1.
Front Biosci. 2008 May 1;13:4687-706. doi: 10.2741/3033.
Speciation of clawed frogs occurred through bifurcation and reticulation of evolutionary lineages, and resulted in extant species with different ploidy levels. Duplicate gene evolution and expression in these animals provides a unique perspective into the earliest genomic transformations after vertebrate whole genome duplication (WGD) and suggests that functional constraints are relaxed compared to before duplication but still consistently strong for millions of years following WGD. Additionally, extensive quantitative expression divergence between duplicate genes occurred after WGD. Diversification of clawed frogs was potentially catalyzed by transposition and divergent resolution--processes that occur through different genetic mechanisms but that have analogous implications for genome structure. How sex determination is maintained after genome duplication is fundamental to our understanding of why allopolyploidization is so prevalent in this group, and why clawed frogs violate Haldane's Rule for hybrid sterility. Future studies of expression subfunctionalization in polyploids will shed light on the role and purviews of cis- and trans-regulatory elements in gene regulation.
爪蟾的物种形成是通过进化谱系的分歧和网状化实现的，并导致了具有不同倍性水平的现存物种。这些动物中重复基因的进化和表达为脊椎动物全基因组复制（WGD）后最早的基因组转变提供了独特视角，并表明与复制前相比，功能限制有所放松，但在WGD后的数百万年里仍然持续很强。此外，WGD后重复基因之间出现了广泛的定量表达差异。爪蟾的多样化可能是由转座和分歧解决所催化的——这些过程通过不同的遗传机制发生，但对基因组结构具有类似的影响。基因组复制后性别决定如何维持，对于我们理解为什么异源多倍化在该类群中如此普遍，以及为什么爪蟾违反了关于杂种不育的霍尔丹法则至关重要。未来对多倍体中表达亚功能化的研究将阐明顺式和反式调控元件在基因调控中的作用和范围。
